I assume zmj's point is that we implicitly make this trade-off all the time. For example, cars could be safer, but then they would be more expensive. Anytime we opt for a cheaper car with less safety features, we are making a cost-benefit analysis involving our own lives and the lives of the people who will travel in our car. (Who are probably the most important people to us.) There becomes a point where the actual gains in life-saving potential is negligible, and we don't think it is worth the cost. But we rarely state it that way.
We could easily make cars way, way safer - put a giant, sharp spike sticking out of the center of the steering wheel, pointed at the driver's heart, and forbid seatbelts. Nobody would ever go over 5mph, or put themselves at risk of crashing into anything.
This is one of the better comments I've seen lately - perfect execution of the "take the parent post's example to an absurd, irrelevant extreme and say Q.E.D."-style comment that seems to be all the rage around here lately. Love it, A+!
You have completely botched this example. This example is useful to explain why airbags increase collisions. Putting a spear in cars would not make cars safer.
There is a major difference. The number of traffic accidents did not change significantly from 1990 to 2009, but the number of deaths from traffic accidents dropped 23%[1]. This is most likely due to cars being built in a way so that their passengers are more likely to survive accidents.
